Abstract

This study examined spatial release from masking (SRM) when a target talker was masked by competing talkers or by other types of sounds. The focus was on the role of interaural time differences(ITDs) and time-varying interaural level differences (ILDs) under conditions varying in the strength of informational masking (IM). In the first experiment, a target talker was masked by two other talkers that were either colocated with the target or were symmetrically spatially separated from the target with the stimuli presented through loudspeakers. The sounds were filtered into different frequency regions to restrict the available interaural cues. The largest SRM occurred for the broadband condition followed by a low-pass condition. However, even the highest frequency bandpass-filtered condition (3–6 kHz) yielded a significant SRM. In the second experiment the stimuli were presented via earphones. The listeners identified the speech of a target talker masked by one or two other talkers or noises when the maskers were colocated with the target or were perceptually separated by ITDs. The results revealed a complex pattern of masking in which the factors affecting performance in colocated and spatially separated conditions are to a large degree independent.

Received 24 September 2009Revised 14 July 2010Accepted 17 July 2010Published online 18 October 2010

Acknowledgments:

This work was supported by AFOSR Grant No FA9550-08-1-0424 and by Grant Nos. DC004545, DC00100 and DC004663 from NIH/NIDCD. Virginia Best was also supported by a University of Sydney Postdoctoral Research Fellowship and Nicole Marrone was supported by Grant No. DC004453 from NIH/NIDCD. The authors thank Suzanne Carr Levy for her comments on an earlier version of this manuscript and Nathaniel I. Durlach for many interesting discussions of this work.